AC condition

I am assuming you have central A/C. If this is also a large window A/C over 12000 BTU this will still be cost effective. If it is cause by a small window unit, buy a new one.
I suggest you have your electical check to see if the breaker teminals, outlets for window unit or disconnect at your central A/C connections are loose.
This can also save you money as loose connections cause wires to heat up and draw more current.
I tighten my electrical connections every two years or so, especially on large appliance feeds and my sound room.

Run a dedicated line to your electronics and make sure the AC is on the other side of the panel from the dedicated line.

If you can't run a dedicated line, then have an electrician move your audio line to the other side of the panel, isolating it from the AC line.

Perhaps if an old home, you may need to update the panel or you could add on a poney panel and isolate some lines.

Make sure the wiring in the walls meets code,they can get pretty hot if they aren't the proper guage and AC is drawing a lot of juice.

Old homes have been known to lack the proper guage wiring for all of todays conveniences.

Assumption is not the solution to the problem as in such cases you need you consult with a professional ac repair who can check in it why this problem has been occurred . This might be the voltage drop problem because they both are in the same outlet. So in such problem having the professional advice is really helpful.

Pepp-

consult your local electrician for a dedicated line for your system.